Photoresist resin composition and method of forming patterns by using the same

ABSTRACT

A method for forming a pattern includes forming a photosensitive film by coating a photosensitive resin composition on a substrate, exposing the photosensitive film to light through a mask that includes a light transmission region and a non-light transmission region, coating a developing solution on the photosensitive film, and forming a photosensitive film pattern by baking the photosensitive film, wherein the photosensitive resin composition includes an alkali soluble base resin, a photoacid generator and a photoactive compound.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 13/224,935 filed on Sep. 2, 2011, which claims priority to andthe benefit of Korean Patent Application No. 10-2011-0025286 filed inthe Korean Intellectual Property Office on Mar. 22, 2011, and all thebenefits accruing therefrom under 35 U.S.C. §119, the contents of theprior applications being herein incorporated by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

A photosensitive resin composition and a method for forming a pattern byusing the same are provided.

(b) Description of the Related Art

Display devices such as a liquid crystal displays (LCD) and organiclight emitting diode displays include a plurality of thin films such asa conductive layers, a semiconductor layer and insulating layers.

In a thin film transistor array panel, a gate conductive layer, asemiconductor layer, a data conductive layer, and additional thin filmssuch as a pixel electrode layer may be formed, and these thin films areusually patterned by using photolithography. Photolithography is amethod for etching thin films that uses a mask. The etchant etches areasnot covered by the mask to form a pattern in the thin film. The mask isformed by exposing and developing a photosensitive film that is coatedon the thin film, to form a pattern having a predetermined shape in thephotosensitive film. The photosensitive film may include aphotosensitive resin composition.

Methods for finely patterning thin films have been studied in order toimprove the quality of display devices. In order to finely pattern athin film, the photosensitive film needs to be finely patterned. Whetheror not a photosensitive film is capable of being finely patterned islargely determined by the compounds that form the photosensitive resincomposition.

The above information disclosed in this Background section is only forenhancement of understanding of the background and therefore it maycontain information that does not form the prior art that is alreadyknown to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

A photosensitive resin composition including an alkali soluble baseresin, a photoacid generator, a photoactive compound, and a phenol-basedcompound including a hydrophobic group is provided.

The phenol-based compound may be a compound represented by the followingFormula 1.

wherein R₁ to R₃ are independently a substituted or unsubstituted C₁-C₁₀alkyl group, and n1 to n3 are independently an integer of 1 to 5.

The alkali soluble base resin may be a tandem type resin.

The tandem type resin may include a high molecular weight resin, a lowmolecular weight resin, and a medium molecular weight resin, and themedium molecular weight resin may be included in a smaller amount thaneach of the high molecular weight resin and the low molecular weightresin. The high molecular weight resin may have a molecular weight ofabout 5000 g/mol or more, the low molecular weight resin may have amolecular weight of about 500 g/mol or less, and the medium molecularweight resin may have a molecular weight of about 500 g/mol to about5000 g/mol.

The base resin may be about 100 parts by weight, the photoacid generatormay be about 0.01 to about 20 parts by weight, the photoactive compoundmay be about 0.1 to about 30 parts by weight and the phenol-basedcompound may be about 0.01 to about 20 parts by weight.

In another aspect, a method for forming a pattern is provided, themethod including: forming a photosensitive film by coating aphotosensitive resin composition on a substrate, exposing thephotosensitive film to light through a mask, the mask including a lighttransmission region and a non-light transmission region, coating adeveloping solution on the photosensitive film, and forming aphotosensitive film pattern by baking the photosensitive film, whereinphotosensitive resin composition includes an alkali soluble base resin,a photoacid generator and a photoactive compound.

The photosensitive film pattern may have a rectangular cross-section.

The method for forming the pattern may further include forming a thinfilm on the substrate. The thin film may be a pixel electrode of aliquid crystal display, and the pixel electrode may include a finebranch electrode.

A width of the fine branch electrode may be about 2 μm or less.

The photosensitive resin composition may further include a phenol-basedcompound including a hydrophobic group.

According to the method, it is possible to finely pattern a thin filmand improve transmittance of a display device by finely patterning apixel electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a view schematically illustrating a photosensitive filmpattern according to an exemplary embodiment, and FIG. 1B is a viewschematically illustrating a known photosensitive film pattern.

FIG. 2A is a graph illustrating solubility with respect to a developingsolution of a photosensitive resin composition according to theexemplary embodiment for each step of a pattern forming process, andFIG. 2B is a graph illustrating solubility with respect to a developingsolution of a known photosensitive resin composition for each step of apattern forming process.

FIG. 3 is a gel permeation chromatography (GPC) graph of a base resinaccording to the exemplary embodiment.

FIG. 4 is a gel permeation chromatography graph of a base resinaccording to another exemplary embodiment.

FIG. 5 is an equivalent circuit diagram of a liquid crystal displayaccording to an exemplary embodiment.

FIG. 6 is a layout view of a liquid crystal display according to anexemplary embodiment.

FIG. 7 is a cross-sectional view that is taken along the line VII-VII ofthe liquid crystal display of FIG. 6.

FIG. 8 is a cross-sectional view that is taken along the line VII-VII ofthe liquid crystal display of FIG. 6.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsare shown. As those skilled in the art would realize, the describedembodiments may be modified in various different ways, all withoutdeparting from the spirit or scope of the present invention. Thedrawings and description are to be regarded as illustrative in natureand not restrictive. Like reference numerals are used to designate likeelements throughout the specification. Furthermore, detailed descriptionof widely known technology will be omitted.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. It will be understood that when an elementsuch as a layer, film, region, or substrate is referred to as being “on”another element, it may be directly on the other element, or interveningelements may also be present. In contrast, when an element is referredto as being “directly on” another element, there are no interveningelements present. It will be understood that when an element such as alayer, film, region, or substrate is referred to as being “beneath”another element, it may be directly beneath the other element, orintervening elements may also be present. In contrast, when an elementis referred to as being “directly beneath” another element, there are nointervening elements present.

In the present specification, unless otherwise specifically stated, theterm “substituted” means that a matter is substituted by halogen, aC₁-C₂₀ haloalkyl group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, aC₆-C₃₀ aryl group, or a C₆-C₃₀ aryloxy group.

FIG. 1A is a view schematically illustrating a photosensitive filmpattern according to an exemplary embodiment, and FIG. 1B is a viewschematically illustrating a known photosensitive film pattern. FIG. 2Ais a graph illustrating solubility with respect to a developing solutionof a photosensitive resin composition according to the exemplaryembodiment for each step of a pattern forming process, and FIG. 2B is agraph illustrating solubility with respect to a developing solution of aknown photosensitive resin composition for each step of a patternforming process.

With reference to FIG. 1A, a photosensitive film pattern 20 is disposedon a substrate 10. The substrate 10 may include plastic or glass. A thinfilm to be patterned may be disposed on the substrate 10. The thin filmto be patterned may be, for example, a metal layer or a semiconductorlayer. The photosensitive film is formed by coating the photosensitiveresin composition onto the substrate 10, and the photosensitive filmpattern 20 may be formed through exposure and developing processes. InFIG. 1A, a mask (not shown) is used when the photosensitive film isexposed, and the mask includes a light transmission region and anon-light transmission region (i.e., a light blocking region). The lighttransmission region is a region where all the light is transmitted, andthe non-light transmission region is a region where light is nottransmitted, but is blocked. The region where the photosensitive filmpattern 20 is disposed may correspond to the non-light transmissionregion of the mask, and the region where the photosensitive film pattern20 is not disposed may correspond to the light transmission region ofthe mask.

With reference to FIG. 1A, it may be seen that the photosensitive filmpattern 20 has an approximately rectangular cross-section, and even asthe width of the photosensitive film pattern 20 is decreased (from 5 μmto 2 μm), the rectangular shape of the photosensitive film pattern 20 ismaintained. Accordingly, a thin film having a fine pattern may be formedby using the fine photosensitive film pattern 20. For example, a thinfilm pattern having a width of approximately 2 μm or less may be formed.

The method for obtaining the photosensitive film pattern 20 may beexplained with reference to FIG. 2A. FIG. 2A shows the dissolution rateof a photosensitive resin film of an exemplary embodiment in fourdifferent states (which will be explained in more detail below): theresin alone; the non-exposure portion of the resin which includes aphotoacid generator (PAG) and a photoactive compound (PAC); the exposureportion of the resin which includes exposed PAG and exposed PAC; and theexposure portion of the resin which includes exposed PAG and exposed PACafter a post exposure baking process. FIG. 2B, for comparison, shows thedissolution rate of a known photosensitive resin in four states: theresin alone; the non-exposure portion of the resin which includes a PAG;the exposure portion of the resign which includes PAG; and the exposureportion of the resin which includes PAG after a post exposure bakingprocess.

The photosensitive film pattern 20 has an approximately rectangularcross-section even at very small widths because, with reference to FIG.2A, the developing speed of the photosensitive resin composition at thenon-exposure portion of the photosensitive film and the developing speedin the developing solution of the photosensitive resin composition atthe exposure portion of the photosensitive film are significantlydifferent from each other. The developing speed in the developingsolution is proportional to solubility of the photosensitive resincomposition in the developing solution. In other words, the non-exposureportion in the photosensitive film, which corresponds to the non-lighttransmission region of the mask and is therefore not exposed to light,has, as shown in FIG. 2A, a low solubility to the developing solution.Therefore, when the developing solution is coated onto the non-exposureportion of the photosensitive film, the upper part of the non-exposureportion of the photosensitive film may be only slowly developed.Accordingly, because the amount of the photosensitive film removed bythe developing solution is small at the upper part of the non-exposureportion of the photosensitive film, the non-exposure portion of thephotosensitive film may have an approximately rectangular cross-section.Thus, as shown in FIG. 1A, it is possible to form the photosensitivefilm pattern 20 having an approximately rectangular cross-section. Inaddition, the exposure portion in the photosensitive film, whichcorresponds to the light transmission region of the mask and is exposedto light has, as shown in FIG. 2A, a large solubility to the developingsolution. Therefore, when the developing solution is coated onto theexposure portion of the photosensitive film, the exposure portion of thephotosensitive film may be rapidly developed. Accordingly, because theamount of photosensitive film removed by the developing solution in theexposure portion is large, the exposure portion of the photosensitivefilm may be removed in a groove form and have an approximatelyrectangular cross-section.

On the other hand, referring to FIG. 1B, the photosensitive film pattern20 in the known art has an approximately trapezoidal, and eventriangular, cross-section. Because the amount of photosensitive filmremoved by the developing solution is large at the upper part of thenon-exposure portion, as the width of the photosensitive film pattern 20is decreased, the rectangular shape of the photosensitive film pattern20 is not maintained. Accordingly, it is difficult to form a thin filmhaving a fine pattern. For example, it is difficult to form a thin filmpattern having a width of approximately 2 μm or less. With reference toFIG. 2B, the photosensitive film pattern 20 has an approximatelytrapezoidal cross-section because the difference between the developingspeed in the developing solution of the photosensitive resin compositionat the non-exposure portion of the photosensitive film and thedeveloping speed in the developing solution of the photosensitive resincomposition at the exposure portion of the photosensitive film is muchsmaller than the case shown in FIG. 2A.

The photosensitive resin composition of the exemplary embodiments mayinclude a base resin, a photoacid generator, a photoactive compound anda solvent. With reference to FIG. 2A, if a photoacid generator (PAG) anda photoactive compound (PAC) are added to an alkali soluble base resin,because the photoacid generator and the photoactive compound are notalkali soluble, the solubility of the photosensitive resin compositionin the developing solution is decreased. Accordingly, the photosensitivefilm pattern 20 having the approximately rectangular cross-section maybe formed, and the fine thin film may be formed.

Moreover, if a phenol-based compound that includes a hydrophobic groupis added with the photoacid generator and the photoactive compound, thesolubility of the photosensitive resin composition in the developingsolution may be further reduced, and an even finer thin film pattern maybe formed. For example, the phenol-based compound including ahydrophobic group may be a compound represented by the following Formula1.

wherein R₁ to R₃ are independently a substituted or unsubstituted C₁-C₁₀alkyl group, and n1 to n3 are independently an integer of 1 to 5.

In addition, if a tandem type base resin in which a high molecularweight base resin and a low molecular weight base resin are mixed witheach other is used, the solubility of the photosensitive resincomposition to the developing solution may be even further reduced, anda finer thin film pattern may be formed. For example, the high molecularweight base resin may have a molecular weight of approximately 5000g/mol or more, the low molecular weight may be approximately 500 g/molor less, and the medium molecular weight may be approximately 500 to5000 g/mol. FIGS. 3 and 4 are gel permeation chromatography (GPC) graphof a base resins with different molecular weight distributions. FIG. 3is a view that illustrates a molecular weight distribution of a normalbase resin, and FIG. 4 is a view that illustrates a molecular weightdistribution of a tandem type base resin that may be used in thephotosensitive resin composition.

Moreover, if the photoacid generator, the photoactive compound, and thehydrophobic phenol-based compound are used together with the tandem typebase resin, the solubility of the photosensitive resin composition tothe developing solution may be further lowered, and an even finer thinfilm pattern may be formed.

Referring again to FIG. 2A, the solubility of the photosensitive resincomposition to the developing solution at the non-exposure portion ofthe photosensitive film is reduced as compared to the resin plus PAGalone illustrated in FIG. 2B, but the solubility of the photosensitiveresin composition to the developing solution at the exposure portion ofthe photosensitive film is increased as compared to the resin plus PAGalone illustrated in FIG. 2B.

Use of the photoactive compound PAC with the photoacid generator PAGincreases the developing speed of the exposure portion of thephotosensitive film. At the exposure portion of the photosensitive film,the photoactive compound PAC is dissolved and a hydrogen ion isgenerated from the photoacid generator by an exposure process. Thus, thesolubility of the photosensitive resin composition to the developingsolution at the exposure portion of the photosensitive film may beincreased by decomposing the photoactive compound. The solubility of thephotosensitive resin composition in which the photoactive compound andthe photoacid generator are included may be larger than the solubilityof the photosensitive resin composition in which the photoacid generatoris included without the photoactive compound.

Next, at the exposure portion of the photosensitive film, the solubilityto the developing solution can be rapidly increased by a baking process,and this is because the hydrophobic group of the photoacid generator isseparated. This baking process is also called a post exposure baking(PEB) process.

As a difference between the solubility to the developing solution of thenon-exposure portion of the photosensitive film and the solubility tothe developing solution of the exposure portion of the photosensitivefilm in the post-exposure baking process is increased, thephotosensitive film pattern 20 may have a cross-section shape that ismuch closer to the rectangular shape, and the thin film may be morefinely patterned.

The composition of the photosensitive resin composition will bedescribed in detail.

The photosensitive resin composition includes a base resin, a photoacidgenerator, a photoactive compound, and a solvent.

The base resin is an alkali soluble resin. For example, the base resinmay be a novolac-based resin. In addition, the base resin may be, forexample, a tandem type base resin in which a high molecular weight baseresin and a low molecular weight base resin are mixed with each other,and the solubility of the non-exposure portion of the photosensitivefilm to the developing solution may be reduced by the tandem type baseresin. The tandem type base resin may have various molecular weightdistributions according to required characteristics such as sensitivity,close contacting property, and heat resistance of the photosensitiveresin composition. For example, the high molecular weight base resin maybe about 50 to about 100 parts by weight, the medium molecular weightbase resin may be about 0 to about 50 parts by weight, and the lowmolecular weight base resin may be about 0 to about 30 parts by weight.

The photoacid generator is a compound that generates an acid whenirradiated with light. For example, the photoacid generator may be oniumsalt, aromatic diazonium salt, sulfonium salt, triarylsulfonium salt,diarylsulfonium salt, monoarylsulfonium salt, iodine salt, diaryliodinesalt, nitrobenzyl ester, disulfone, diazo-disulfone, sulfonate,trichloromethyl triazine, N-hydroxysuccinimide triplate,phthalimidotrifluoromethane sulfonate, dinitrobenzyl tosylate,n-desyldisulfone, naphthylimidotrifluoromethane sulfonate,diphenyliodine salt hexafluorophosphate, diphenyliodine salthexafluorofluoroarcenate, diphenyliodine salt hexafluoroanthymonate,diphenylparamethoxyphenyl triplate, diphenylparatoluenyl triplate,triphenylsulfonium triplate, or dibutylnaphthylsulfonium triplate, andone or more photoacid generators may be used in combination with eachother.

The photoactive compound is a compound that is decomposed by light. Forexample, the photoactive compound may be2,3,4,4′-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate,and 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate,and one or more photoactive compounds may be used in combination witheach other.

The photosensitive resin composition may further include a phenol-basedcompound having a hydrophobic group, and the solubility of thenon-exposure portion of the photosensitive film to the developingsolution may be reduced by the phenol-based compound having ahydrophobic group. For example, the phenol-based compound including thehydrophobic group may be a compound represented by the above Formula 1.

One or more organic solvents may be used as the solvent, and the solventis not particularly limited.

The photosensitive resin composition may include about 100 parts byweight of the base resin, about 0.01 to about 20 parts by weight of thephotoacid generator, about 0.1 to about 30 parts by weight of thephotoactive compound and about 0.01 to 2 about 0 parts by weight of thephenol-based compound including the hydrophobic group.

When the photoacid generator is used in a range of about 0.01 to about20 parts by weight and the photoactive compound is used in the range ofabout 0.1 to about 30 parts by weight, the solubility of thephotosensitive resin composition to the developing solution may bereduced. Moreover, when the phenol-based compound including thehydrophobic group is used in the range of about 0.01 to about 20 partsby weight, the solubility of the photosensitive resin composition to thedeveloping solution may be further reduced.

A method for forming a pattern by using the photosensitive resincomposition will be described in detail.

With reference to FIG. 1A, the method for forming the pattern includesforming the photosensitive film by coating the photosensitive resincomposition on the substrate having the thin film 10.

Next, the method for forming the pattern includes exposing thephotosensitive film to light through a mask (not shown), which includeslight transmission regions and non-light transmission (i.e., lightblocking) regions. The mask and photosensitive film may then beirradiated with, for example, ultraviolet rays. In this case, when thephotoacid generator is decomposed by exposure to light at the exposureportion of the photosensitive film, an acid is generated from thephotoactive compound.

Next, the method for forming the pattern includes coating a developingsolution on the exposed photosensitive film. In this case, the exposureportion of the photosensitive film may be dissolved by the developingsolution and removed.

Next, the method for forming the pattern includes baking thephotosensitive film. In this case, the exposure portion of thephotosensitive film is almost removed, and the non-exposure portion ofthe photosensitive film is not almost removed, such that thephotosensitive film pattern 20 may be formed.

In order to pattern the thin film, the method for forming the patternmay include forming the thin film on the substrate 10, and forming thephotosensitive film on the thin film.

A liquid crystal display that includes a finely patterned pixelelectrode formed by using the method for patterning thin films using thephotosensitive resin composition will be described in detail withreference to FIG. 5 to FIG. 8.

FIG. 5 is an equivalent circuit diagram of the liquid crystal displayaccording to an exemplary embodiment, FIG. 6 is a layout view of aliquid crystal display according to an exemplary embodiment, FIG. 7 is across-sectional view that is taken along the line VII-VII of the liquidcrystal display of FIG. 6, and FIG. 8 is a cross-sectional view that istaken along the line VIII-VIII of the liquid crystal display of FIG. 6.

With reference to FIG. 5, the liquid crystal display includes a firstdisplay panel 100 and a second display panel 200 facing each other, anda liquid crystal layer 3 disposed between the first display panel 100and the second display panel 200. The first display panel 100 includessignal lines including a plurality of gate lines GL, a plurality pairsof data lines DLa and DLb and a plurality of storage electrode lines SL,and a plurality of pixels PX connected thereto.

A pixel PX includes a pair of subpixels PXa and PXb, and the subpixelsPXa and PXb include switching elements Qa and Qb, liquid crystalcapacitors Clca and Clcb and storage capacitors Csta and Cstb.

The switching elements Qa and Qb are a thin film transistor that areprovided on the first display panel 100, and a control terminal thereofis connected to the gate line GL, an input terminal is connected to thedata lines DLa and DLb, and an output terminal is connected to theliquid crystal capacitors Clca and Clcb and the storage capacitors Cstaand Cstb.

The liquid crystal capacitors Clca and Clcb have subpixel electrodes 191a and 191 b and a common electrode 270 as two terminals, and a liquidcrystal layer 3 between the two terminals is used as a dielectricmaterial.

The storage capacitors Csta and Cstb, which act as an auxiliarycapacitor of the liquid crystal capacitors Clca and Clcb, are formed byoverlapping the storage electrode line SL provided on the first displaypanel 100 and the subpixel electrodes 191 a and 191 b with an insulatordisposed therebetween, and a predetermined voltage such as a commonvoltage Vcom is applied to the storage electrode line SL.

With reference to FIG. 6 to FIG. 7, a plurality of gate lines 121 and aplurality of storage electrode lines 131 and 135 are formed on aninsulation substrate 110 made of glass and plastic. A gate line 121transfers a gate signal and extends in a row direction. Each gate line121 includes a plurality of first and second gate electrodes 124 a and124 b protruding upward from the gate line 121 in a plan view.

The storage electrode lines 131 and 135 include a branch line 131 thatextends substantially parallel to the gate line 121 and a plurality ofstorage electrodes 135 extending therefrom. The shape and disposition ofthe branch line 131 and the storage electrode 135 may be variouslychanged. The storage electrode line 131 and the storage electrode 135may also be omitted.

A gate insulating layer 140 is formed on the gate line 121 and thestorage electrode lines 131 and 135. The gate insulating layer 140 mayinclude silicon nitride (SiNx) or silicon oxide (SiO₂).

A plurality of semiconductors 154 a and 154 b including hydrogenatedamorphous silicon (amorphous silicon is abbreviated to a-Si) orpolysilicon are formed on the gate insulating layer 140.

A plurality pairs of ohmic contacts 163 a, 165 a, and 165 b are formedon the semiconductors 154 a and 154 b, and the ohmic contacts 163 a, 165a, and 165 b may include a material such as n+ hydrogenated amorphoussilicon where metal silicide or n-type impurity is doped in a highconcentration.

A plurality pairs of data lines 171 a and 171 b and a plurality pairs offirst and second drain electrodes 175 a and 175 b are formed on theohmic contacts 163 a, 165 a, and 165 b and the gate insulating layer140. In addition, a storage voltage supply line (not shown) is formed onthe same layer as the data lines 171 a and 171 b around a peripheralarea. The storage voltage supply line is formed in an approximatelycolumn direction, and a plurality of storage electrode lines 131 areelectrically connected thereto.

The data lines 171 a and 171 b extend in a column direction and crossbranch lines 131 and the gate line 121. The data lines 171 a and 171 bextend toward the first and the second gate electrodes 124 a and 124 band include first and second source electrodes 173 a and 173 b, whichare bent in a U-shape, and the first and the second source electrodes173 a and 173 b face the first and the second drain electrodes 175 a and175 b on the first and the second gate electrodes 124 a and 124 b.

The first and the second gate electrodes 124 a and 124 b, the first andthe second source electrodes 173 a and 173 b and the first and thesecond drain electrodes 175 a and 175 b form first and second thin filmtransistors Qa and Qb in conjunction with the first and the secondsemiconductors 154 a and 154 b. The channels of the thin filmtransistors Qa and Qb are formed in the first and the secondsemiconductors 154 a and 154 b between the first and the second sourceelectrodes 173 a and 173 b and the first and the second drain electrodes175 a and 175 b. The first and the second drain electrodes 175 a and 175b are each connected to pixel electrodes 191 a and 191 b of the liquidcrystal display to apply a driving voltage.

The ohmic contacts 163 a, 165 a, and 165 b exist between thesemiconductors 154 a and 154 b therebelow and the data lines 171 a and171 b and the drain electrodes 175 a and 175 b thereon, and reducecontact resistance therebetween.

With the exception of channel portions of the first and the secondsemiconductors 154 a and 154 b, plane shapes of three layers of thefirst and the second semiconductors 154 a and 154 b, the ohmic contacts163 a, 165 a, and 165 b, the data lines 171 a and 171 b including thefirst and the second source electrodes 173 a and 173 b, and the firstand the second drain electrodes 175 a and 175 b are substantially thesame as each other. In this case, the three layers are formed by usingone mask. However, the first and the second semiconductors 154 a and 154b, and the ohmic contacts 163 a, 165 a, and 165 b may be an island type.The shape of the three layers may be variously changed.

The lower layer 180 p including silicon nitride, and silicon oxide isformed on the data lines 171 a and 171 b, the drain electrodes 175 a and175 b and the exposed semiconductors 154 a and 154 b.

A blue color filter 230B, a green color filter 230G and a red colorfilter 230R are formed on the lower layer 180 p. Each color filter 230B,230G, and 230R may have a band shape. In addition, because each colorfilter 230B, 230G, and 230R may be printed by an inkjet process,processability is excellent.

An upper layer 180 q is formed on each color filter 230B, 230G, and230R. The upper layer 180 q may include silicon oxide, silicon nitride,and photosensitive organic materials. The upper layer 180 q serves toplanarize the thin film transistor array panel.

Light blocking members 220 a and 220 b are formed between the lowerlayer 180 p and the upper layer 180 q. The light blocking members 220 aand 220 b extend in an approximate column direction parallel to the datalines 171 a and 171 b, and include a protruding part 220 b covering thefirst and the second thin film transistors Qa and Qb. The light blockingmember 220 may prevent light leakage by covering each color filter 230B,230G, and 230R.

A spacer 320 is formed on the same layer as the light blocking member220 between the lower layer 180 p and the upper layer 180 q. However,the spacer 320 may be formed on the other layer in respects to adifferent layer from the light blocking member 220. The spacer 320serves to maintain a gap of the liquid crystal layer 3, and may be acolumn spacer(columnar spacer) 320. The column spacer 320 may bepositioned between the first and the second thin film transistors Qa andQb.

The light blocking member 220 and the column spacer 320 may include thesame material, and may be formed in different thicknesses by using ahalftone mask. Besides, the disposition and the shape of the columnspacer 320 may be variously changed.

A plurality of pixel electrodes 191 are formed on the upper layer 180 q.A plurality of pixel electrodes 191 may include the same material suchas ITO, and IZO, and may be formed in the same process.

Each pixel electrode 191 includes first and second subpixel electrodes191 a and 191 b separated from each other with a gap 91 disposedtherebetween.

The whole shape of the first and the second subpixel electrodes 191 aand 191 b is a quadrangle. An area occupied by the second subpixelelectrode 191 b in the whole pixel electrode 191 may be larger than anarea occupied by the first subpixel electrode 191 a. Each of the firstand the second subpixel electrodes 191 a and 191 b includes a mainbranch and a subbranch. The main branch is approximately parallel to thegate line 121 or the data line 171. The subbranch is a fine branchhaving a comb shape.

The width of the subbranch patterned by using the photosensitive resincomposition may be approximately 2 μm or less, and an interval betweenthe subbranches may be approximately 2 μm or less. In the case where thewidth of the subbranch is approximately 2 μm or less, transmittance ofthe display device may be improved. For example, in the case where thethickness of the liquid crystal layer is approximately 2.9 μm, thetransmittance of the display device may be about 88% when the width ofthe subbranch is approximately 3 μm, and the transmittance of thedisplay device may be about 95% when the width of the subbranch isapproximately 2 μm.

The first and the second pixel electrodes 191 a and 191 b are physicallyand electrically connected to the first and the second drain electrodes175 a and 175 b through contact holes 185 a and 185 b and receive thedata voltage from the first and the second drain electrodes 175 a and175 b.

A lower alignment layer 11 is formed on the plurality of pixelelectrodes 191.

The second display panel 200 includes a common electrode 270 that is notpatterned.

A liquid crystal layer 3 may include a reactive mesogen and a liquidcrystal molecule is disposed between the first display panel 100 and thesecond display panel 200.

While this disclosure has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the disclosure, including the appended claims.

What is claimed is:
 1. A method for forming a pattern, the methodcomprising: forming a photosensitive film by coating a photosensitiveresin composition on a substrate; exposing the photosensitive film tolight through a mask, the mask including a light transmission region anda non-light transmission region; coating a developing solution on thephotosensitive film; and forming a photosensitive film pattern by bakingthe photosensitive film, wherein photosensitive resin compositionincludes an alkali soluble base resin, a photoacid generator and aphotoactive compound.
 2. The method of claim 1, wherein: thephotosensitive film pattern has a substantially rectangularcross-section.
 3. The method of claim 1, further comprising: forming athin film on the substrate.
 4. The method of claim 3, wherein: the thinfilm is a pixel electrode of a liquid crystal display, and the pixelelectrode includes a fine branch electrode.
 5. The method of claim 4,wherein: a width of the fine branch electrode is about 2 μm or less. 6.The method of claim 1, wherein: the photosensitive resin compositionfurther includes a phenol-based compound including a hydrophobic group.7. The method of claim 6, wherein: the phenol-based compound is acompound represented by the following Formula 1:

wherein R₁ to R₃ are independently a substituted or unsubstituted C₁-C₁₀alkyl group, and n1 to n3 are independently an integer of 1 to
 5. 8. Themethod of claim 1, wherein: the alkali soluble base resin is a tandemtype resin.
 9. The method of claim 8, wherein: the tandem type resinincludes a high molecular weight resin, a low molecular weight resin,and a medium molecular weight resin, wherein the medium molecular weightresin is included in a smaller amount than each of the high molecularweight resin and the low molecular weight resin.
 10. The method of claim9, wherein: the high molecular weight resin has a molecular weight ofabout 5000 g/mol or more, the low molecular weight resin has a molecularweight of about 500 g/mol or less, and the medium molecular weight resinhas a molecular weight of about 500 g/mol to about 5000 g/mol.
 11. Themethod of claim 1, wherein: the base resin is about 100 parts by weight,the photoacid generator is about 0.01 to about 20 parts by weight, thephotoactive compound is about 0.1 to about 30 parts by weight and thephenol-based compound is about 0.01 to about 20 parts by weight.